SARMs: A Potential Way To Build More Muscle

Performance-enhancing drugs are a touchy subject (just ask Lance Armstrong). Many people consider them cheating, and the most infamous varieties can be seriously dangerous – steroids come to mind.

The last ten years have given rise to an exciting new class of performance-enhancing drug. It’s a collection of compounds called selective androgen receptor modulators (SARMs). The limited research on SARMs looks promising so far. They appear to build muscle and burn fat at a level comparable to steroids, but without the ball-shrinking, liver-destroying, unsightly body hair-growing effects. They act on your hormones, but in a very targeted way, and they show potential if you want to rapidly build muscle and shed fat.

That said, many SARMs studies are in rats, and there haven’t been any long-term human experiments looking at the safety of SARMs. There could be side effects we don’t know about yet. Playing with your hormones is risky. At the very least, though, SARMs are interesting compounds that merit discussion.

SARMs fall firmly into the realm of experimental biohacking. These are riskier than most of the hacks I talk about. This article presents both the good and bad sides of SARMs. I hope it helps you make an informed decision about whether or not to try them.

Disclaimer: SARMs are on the World Anti-Doping Agency’s list of banned substances for athletic competition. If you’re a competitive athlete, you shouldn’t take these. If you’re a curious self-experimenter looking to upgrade your physical performance, though, SARMs may be worth considering.

How SARMs work (and why they may be better than steroids)

Using steroids to boost your hormones is like trying to tweak a microchip with a sledgehammer. Steroids help you build muscle by increasing testosterone, which then increases protein synthesis in your cells, building muscle and burning fat. That’s considered the anabolic side of steroids, and it’s great.

But steroids also interact with your liver, your prostate, your heart, your sex organs (which leads to ball shrinkage in men and clitoral enlargement in women), and your secondary sex characteristics (voice depth, body hair growth, man boobs, acne, etc.). All these side effects are the androgenic part of steroids.

The issue with steroids is that they have an anabolic-to-androgenic ratio of 1:1. That means they are just as likely to, say, shrink your balls or enlarge your clitoris as they are to build muscle – unless you’re taking bioidentical testosterone to maintain optimal hormone levels, with a doctor’s careful supervision (I’ve been doing this for years and I’ve never had side effects. You can read about hacking testosterone here).

This is where SARMs innovate. They’re far more selective than steroids, boasting anabolic-to-androgenic ratios starting at 3:1 and going as high as 90:1. That means you can still get muscle growth and fat loss, but SARMs won’t give you man boobs or turn you into the bearded lady. You can also take SARMs orally. No need for injections.

SARMs are also legal, as long as you buy them “for research purposes only.” You’ll notice SARMs retailers include disclaimers like “for lab research purposes only” and “not for human consumption.” They do this in case laws change, so they don’t get in trouble with the government.

There are about a dozen SARMs in either clinical (human) trials or pre-clinical (animal) trials. This article will cover pros and cons of the most popular ones. Again, this is a little more out there than most of the biohacking I discuss. Proceed at your own risk.

With that in mind, let’s talk about the first SARM on the list: MK-2866.

MK-2866 builds muscle and burns fat

With multiple published human trials under its belt, MK-2866 (also called ostarine) is one of the best-studied SARMs. Those studies found powerful results, too. Ostarine shows no meaningful side effects and is very effective at building muscle.

Elderly men and women who took modest doses of ostarine for 12 weeks grew 3 pounds of muscle and lost a pound of fat, with no changes to diet or exercise [1]. Cancer patients saw nearly identical results along a similar timeframe [2]. There were no side effects in either study.

A pound of muscle a month is about what you would expect with a solid workout routine – but the people taking ostarine in these studies weren’t exercising. Combining the two would be even more powerful, in theory. Pretty impressive.

Side effects of MK-2866

The studies found no side effects. Anecdotally, however, people report short-term testosterone suppression when they take high doses of ostarine for 8-12 weeks. Testosterone rebounded to normal levels within a couple weeks after they stop. The dosage I discuss below is far lower and for a shorter amount of time, but there’s still a risk of short-term T suppression, and possibly other side effects researchers don’t know about yet.

How to dose MK-2866

There haven’t been official dose recommendations for SARMs because they’re so new. The doses in this article are all conservative, and based what on studies and anecdotal reports show to work.

For ostarine, online communities report results at 15-20mg daily for 4 weeks. Time of day doesn’t matter. To be cautious, take at least 4 weeks off so your system balances out before starting another cycle. Ostarine, along with the other SARMs on this list, seems to pair best with regular exercise like lifting and HIIT.

LGD-4033

LGD-4033, also called Ligandrol or Anabolicum, is one of the better studied SARMs. It’s been through multiple human trials, with interesting results:

Healthy men who took LGD-4033 for 21 days saw a significant increase in lean body mass. The only side effect was short-term testosterone suppression (more on that in a second) [3]. One milligram per day was enough to cause significant muscle growth. The higher the dose, the more muscle participants put on.

In another trial, participants took doses as high as 22 mg/day with no side effects or safety issues [3].

LGD-4033 does not appear to stimulate fat loss, so if you take it on its own, it won’t make you leaner – just more muscular.

Side effects of LGD-4033

LGD-4033 will probably suppress your natural testosterone production a bit while you’re on it, although the effects seem to be short-lived [3]. Study participants saw T suppression dependent on dose, but none of them dropped out of the healthy testosterone range, and levels returned to normal within 3 weeks after they stopped taking LGD-4033.

How to dose LGD-4033

Users report success taking 2-5 mg of LGD-4033, in a single daily dose, for 4 weeks. It seems that the higher the dose, the more muscle you put on, and the more your testosterone dips. Some people take up to 15 mg per day for much longer timeframes, but that’s riskier. You don’t want your natural T production to tank entirely. Once your 4 weeks are up, wait at least a month before starting another cycle.

GW501516

GW501516 (Cardarine) doesn’t have any published human studies. In rodents, though, it shows great promise as an exercise mimetic – it lights up many of the same genes you’d activate by going on a run or lifting [4]. That alone wasn’t enough to make much of a change, but when researchers had mice take GW501516 with consistent exercise, results went through the roof:

In mice, GW501516 combined with 4 weeks of regular running increased running time by 68% and running distance by 70%, and doubled overall muscular endurance [4].

In rodents, GW501516 plus exercise increased mitochondrial growth in muscle by ~50% [5], allowing muscles to generate more power without fatiguing.

It also decreased fat while preserving muscle (again, in mice) [4].

GW501516 could be a powerful way to improve performance and shed fat while maintaining muscle. Hopefully human studies will come out soon.

Side effects of GW501516

Shortly after it was classified as a performance-enhancing drug, reports started coming out saying that GW501516 caused cancer in lab rats.

But as with most substances, the devil’s in the dose. Studies did find that GW501516 is carcinogenic…but the rats were taking the human equivalent of 2400 mg a day for 2 years straight [6].

That’s about 240x a normal dose, taken every day, for 104 weeks instead of 4 weeks.

The studies found no evidence that GW501516 causes cancer at a dose you would actually use, or even at doses considerably higher than that. Other rat studies report no side effects, and people in the online SARMs community report none either, including no testosterone suppression. Again, though, that doesn’t mean there aren’t side effects. We may just not know about them. Proceed with caution.

How to dose GW501516

GW501516 works best if you split it into two daily doses. Try 5 mg, morning and afternoon, for a total of 10 mg a day.

Take GW501516 for 4 weeks, then cycle off for at least 4 weeks before starting another round. It pairs well with LGD-4033 and MK-2866. Here’s a good source.

S4

S4 (andarine) was the earliest SARM. It was popular in the 2008 Olympics, before SARMs were banned from professional athletics. Users report modest strength and muscle gain, as well as modest fat loss.

S4 seems to work best if you use it alongside other SARMs. It pairs well with MK-2866 and LGD-4033. Both suppress testosterone at higher doses, a side effect S4 can counter. But S4 carries unique side effects that may make it better to skip.

Side effects of S4

The big side effect with S4 is visual abnormality. There have been no official studies on it, but a lot of users report altered color perception and nighttime blindness (trouble seeing in the dark) after taking S4 for a couple weeks, because one of S4’s metabolites binds to receptors in your eyes. When you also consider that S4 is relatively weak, it begins to look less attractive than other SARMs on this list.

How to dose S4

If you do decide to take S4, go for 50 mg daily, split into two 25 mg doses. As with all the other SARMs on this list, take it daily for 4 weeks, and then wait at least 4 weeks before starting another cycle.

SR9009 for endurance and fat loss…if you inject it

SR9009 (Stenabolic), praised as “exercise in a pill,” seems like the perfect supplement. In mice, it increases endurance and fat burning, decreases inflammation, and stimulates the growth of new mitochondria in muscle cells [7,8]. Obese rats injected with SR9009 lost 60% more weight than rats injected with placebo, without changing diet or exercise.

Assuming SR9009 works in humans too, that sounds great. But the key part of the study is that rats were injected. Taking SR9009 orally is pretty much useless. It has about 2% oral bioavailability, and your system clears that 2% almost immediately [9]. Which is too bad, because most SARM manufacturers sell SR9009 as an oral supplement that’s not suitable for injection. They claim it works; studies show it doesn’t.

You’re better off spending your money on another member of this list, unless you find injection-grade SR9009 and are willing to stick yourself a couple times a day.

Final thoughts

Biohacking is about self-experimentation, and it often carries a bit of risk with it – especially if you’re trying cutting-edge things.

Because they’re so new, SARMs carry more risk than most of the stuff I talk about on this blog. This is a little more out there than eating the Bulletproof Diet or hacking your sleep. Proceed at your own risk, use your judgment, and listen to your body.

Have you tried SARMs? Are you going to start? If so, it’d be great if you shared the good and bad in the comments below. Thanks for reading and happy biohacking.

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Dave Asprey is founder & CEO of Bulletproof, and creator of the widely-popular Bulletproof Coffee. He is a two-time New York Times bestselling author, host of the Webby award-winning podcast Bulletproof Radio, and has been featured on the Today show, Fox News, Nightline, Dr. Oz, and many more.

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